1. Field of the Invention
The present invention generally relates to an apparatus for and a method of controlling a variable valve mechanism of an internal combustion engine and, more particularly, relates to a technique for correcting an open characteristic of an intake valve in accordance with an amount of air passing through the intake valve of an internal combustion engine having a variable valve mechanism for varying the open characteristic of the intake valve.
2. Description of the Related Art
Japanese Unexamined Patent Publication No. 2004-340013 discloses an internal combustion engine having a lift-amount/operation-angle-varying mechanism for continuously varying a lift amount and an operation angle of an intake valve and a phase-varying mechanism for continuously varying a center phase of the operation angle of the intake valve.
The publication also discloses such a technique that, when the intake valve is operated in a region in which the operation angle is lower than a threshold, a correction value for correcting a target operation angle is set, and when the intake valve is operated in a region in which the operation angle is equal to or larger than the threshold, a correction value for correcting a target center phase is set.
However, since an intake air amount changes due to the negative pressure in an intake pipe and the timing of closing an intake valve, even if the region in which a variation in the intake air amount is detected is limited to a low-speed/low-load region, it is difficult to accurately detect any variation in the intake air amount caused by the lift-amount/operation-angle-varying mechanism.